The functions or variables listed here are no longer part of 'gdata'.
aggregate.table(x, by1, by2, FUN=mean, ...)
data to be summarized.
first grouping factor.
second grouping factor.
a scalar function to compute the summary statistics which can
be applied to all data subsets. Defaults to mean.
optional arguments for FUN.
aggregate.table(x, by1, by2, FUN=mean, ...) should be replaced
by tapply(X=x, INDEX=list(by1, by2), FUN=FUN, ...).